New Low-Spin Levels in 72Ge and Discussion of Its Yrast Band Structure*

Abstract

The decay of 72 Ga has been investigated by means of γ-ray spectroscopy. The 72 Ga nuclei were produced through the 71 Ga(n, γ) 72 Ga reaction. The Compton-suppressed spectrometer and High-purity Ge detectors have been used singly and in coincidence, respectively, to study γ-rays in the β - decay of 72 Ga to 72 Ge. 93 γ-rays, among which 7 were observed for the first time, were reported. A decay scheme of 72 Ga including 4 new levels is proposed which accommodates 87 of these transitions. Spins and parities for new levels are proposed from calculated log f t values, modes on the observed decay, and some nuclear reaction experiment results. Combining with the high-spin states observed by the in-beam γ-ray spectroscopy of a previous decay work, the structure of the excited positive-parity yrast states of 72 Ge is discussed in the framework of the projected shell model.